1. Field of the Invention
The present invention relates to a head to write and read data, and more particularly, to a hybrid head to write and reading data, which can record data with a high density and can reproduce high density data.
2. Description of the Related Art
A hard disk drive (HDD) includes a recording medium, where data is recorded, a head to record data on the recording medium, a driver to drive the recording medium and the head, an interface to connect the HDD to a computer, and an electronic circuit to drive and control the other elements.
The head can be called a magneto resistive head or a grand magneto resistive head (GMR), depending on the magnetic sensor used to read the data written on the recording medium. A magneto resistive head, in which a magneto resistive sensor is used, had been widely used until the grand magneto resistive sensor was developed, which is more sensitive than the magneto resistive head. Recently, the grand magneto resistive head using a grand magneto resistive sensor has gradually replaced the magneto resistive head. More recently, a tunnel magneto resistive (TMR) sensor using the TMR sensor has been developed, which is highly anticipated and being scrupulously observed.
A hybrid head to write and read data includes a magneto sensor, which is a data reproducer, and a magneto-optic writer, which is a data recorder. The magneto-optic writer records data on a recording medium by heating a certain portion of the recording medium so that the temperature can exceed Curie's temperature, and thus temporarily lowering the magnetic force of this portion. Accordingly, the magneto-optic writer can reduce the magnitude of the magnetic force required to record data less than that of the magnetic force required for a conventional writer. During this process of recording data using the hybrid head, since data is recorded on the portion of the recording medium which exceeds Curie's temperature, the density of data recorded on the recording medium depends not on the size of a pole that generates a magnetic field between gaps but the width of the heated portion of the recording medium. Therefore, when heating the recording medium with a laser diode, the density of data recorded on the recording medium is determined by the width of a laser beam generated from the laser diode.
Until now, various types of hybrid heads having such characteristics have been suggested, and some of them have been widely used. FIG. 1 is a perspective view of an example of a conventional hybrid head.
In FIG. 1, reference numerals 60 and 61 represent a data recorder and a data reproducer, respectively. The data reproducer 61 includes a first shield layer 80, a second shield layer 85, an insulation layer 86 formed between the first and second shield layers 80 and 85 to have one side facing a recording medium, and a grand magneto resistive element 62 surrounded by the insulation layer 86 and the first and second shield layers 80 and 85. The first shield layer 80 comprises a magnetic material that is conductive. The second shield layer 85, which is also part of the data recorder 60, is formed of the same material as the first shield layer 80 and includes an optic channel 88 formed at its one side. The other side of the second shield layer 85 contacts the grand magneto resistive element 62. The optic channel 88 serves as a waveguide to transmit laser beams used to heat a certain portion of the recording medium formed along the second shield layer 85 to a critical temperature close to the Curie's temperature.
Referring to FIG. 2, the grand magnetic resistive element 62 is formed between a first contact element 82 formed on an end of the first shield layer 80 facing a recording medium and a second contact element 84 formed on the second shield layer 85 to face the first contact element 82. A nonconductive magnetic bias element 89 is formed behind the grand magneto resistive element 62 comprising the first and second shield layers 80 and 85 and the insulation layer 86 so that it can contact the first and second contact elements 82 and 84. The magnetic bias element 89 generates a magnetic biasing field acting toward the grand magneto resistive element 62. In FIG. 2, arrows indicate the magnetic biasing field. The first and second contact elements 82 and 84 are formed of a nonmagnetic material which is conductive.
Referring to FIGS. 1 and 2, the insulation layer 86 is formed on the first shield layer 80 to surround the first and second contact elements 82 and 84 and the grand magneto resistive element 62 and to define a nonmagnetic transducing read gap 87.
Referring to FIG. 1, the data recorder 60 includes first and second pole layers 85 and 96 and coils 94. The first pole layer 85 is formed of the same material as the second shield layer 85, and the second pole layer 96 is formed of the same material as the first shield layer 80 or a material having almost the same conductivity as the first shield layer 80. The ends of the first and second pole layers 85 and 96 are formed apart from each other by as much as a write gap 98. The write gap 98 may be filled with the same material as the insulation layer 86 or a material having almost the same conductivity as the insulation layer 86. The coils 94 are formed between the first and second pole layers 85 and 96 lying across the insulation layer 86.
Referring to FIG. 2, a write circuit 100 used to record data is connected to the coils 94. Current Iw required to record data is applied from the write circuit 100 to the coils 94, and accordingly, a magnetic field is generated around the coils 94. The magnetic field is applied to the write gap 98 along the first and second pole layers 85 and 96, and then desired data is recorded by recording “1” or “0” on a certain region of the recording medium facing the write gap 98 using the magnetic field. Before recording data, the certain region of the recording medium is heated above Curie's temperature. In order to heat the certain region, an optic fiber 90 is formed to extend to an air bearing surface (ABS) of a slider 47 via the optic channel 88 between the first and second pole layers 85 and 96. Energy is provided from a heat source 92 of FIG. 4 to the certain region of the recording medium via the optic fiber 90, and the certain region of the recording medium is heated above Curie's temperature. The heat source 92 is formed on the slider 47 and is connected to the optic fiber 90 (see FIG. 4). A read circuit 102 to reproduce data recorded on the recording medium is connected to the first and second shield layers 80 and 85. The read circuit 102 applies current Ir to the first and second shield layers 80 and 85 when reproducing data. During the reproduction of data recorded on the recording medium, the resistance of the grand magneto resistive element 62 varies depending on the magnetization state of the data, and accordingly, voltage applied to either end of the grand magneto resistive element 62 varies. Due to the voltage variations, electric signals corresponding to the data recorded on the recording medium are generated, and the data can be reproduced in a desired shape using the electric signals. In FIG. 2, “H” represents a gap between the recording medium and a head, in other words, a flying height.
FIG. 3 is a diagram illustrating the data recorder 60 and the data reproducer 61 seen from the recording medium. The structures of the data recorder 60 and the data reproducer 61 become clearer with reference to FIG. 3. In other words, the first shield layer 80 through the second pole layer 96 are sequentially aligned with the end 55 of the slider 47.
In the case of the conventional head to record and reproduce data, data is recorded by heating a certain region of the recording medium above Curie's temperature and thus lowering the magnetic force of this region to record data. Accordingly, it is possible to lower the magnitude of the magnetic field required to record data by several hundreds of Oersteds. However, since a first pole layer is formed around an optic channel, the physical characteristics of the first pole layer may be varied because of heat generated during the recording of data. As a result, the first pole layer may not serve as a magnetic material. The variation in the physical characteristics of the first pole layer may affect a grand magneto resistive element, and thus the grand magneto resistive element may not perform its functions well.
In addition, since the structure of a magneto-optic recording head is almost the same as a recording head of a conventional hard disk driver, it may be difficult to apply photolithography to the magneto-optic recording head.